Continuous process for refining sulfide ores

ABSTRACT

A continuous process for refining metal sulfide ores which is carried out by arranging a smelting furnace and a blister furnace, each maintaining discreteness in the reaction zones, wherein a separator is provided subsequent to the smelting furnace so as to limit the function of the smelting furnace to the melting of the raw material and absorption of the copper content in a slag which slag is formed from a subsequent oxidizing furnace into a matte layer, thus achieving the smelting process at a higher furnace rate. The reaction products in the smelting furnace are all tapped out simultaneously without being separated from each other, and transferred to this separator where they are separated and tapped out individually.

United States Patent [191 Suzuki et al.

[ 1 June 17, 1975 [30] Foreign Application Priority Data May 4, 1972Japan 47-44302 [52] US. Cl. 75/74; 75/72; 75/73;

75/75; 75/76; 266/37 [51] int. Cl C221) 15/00 [58] Field of Search75/76, 72, 74, 73; 266/37 [56] References Cited UNITED STATES PATENTSGarretson 75/74 Stanley 75/73 Gronningsaeter 75/74 Morisaki et al 75/74Primary ExaminerWalter Satterfield Attorney, Agent, or FirmWenderoth,Lind & Ponack (57] ABSTRACT A continuous process for refining metalsulfide ores which is carried out by arranging a smelting furnace and ablister furnace, each maintaining discreteness in the reaction zones,wherein a separator is provided subsequent to the smelting furnace so asto limit the function of the smelting furnace to the melting of the rawmaterial and absorption of the copper content in a slag which slag isformed from a subsequent oxidizing furnace into a matte layer, thusachieving the smelting process at a higher furnace rate, The reactionproducts in the smelting furnace are all tapped out simultaneouslywithout being separated from each other, and transferred to thisseparator where they are separated and tapped out individually.

4 Claims, 5 Drawing Figures SHEET PATENTEDJUN 1 7 I975 FIGZ PATENTEDJUH17 I975 r S 0.13 9

SHEET CONTINUOUS PROCESS FOR REFlNlNG SULFIDE ORES The present inventionrelates to a continuous process for refining sulfide ores. Moreparticularly, the present invention is directed to a continuous methodfor refin ing a sulfide ore of metals such as copper, nickel, and cobaltand an apparatus therefor, wherein the sulfide ore is treated in acontinuous and consistent manner by means of a series of furnaces toobtain the intended metal in large quantity and in the most economicalmanner.

This invention is an improvement in the invention disclosed in U.S. Pat.application Ser. No. 88 l ,226 now U.S. Pat. No. 3.725044.

It is a primary object of the present invention to provide an improvedmethod, wherein each of the process steps essential for the metalrefining is connected to each other so as not to cause any difficulty inthe opera tions as well as in sequence of the operations as a whole. Thestructure of the furnaces for the respective refining process steps andthe devices connecting these furnaces with each other are made simpleand durable to facilitate the construction, operation, and maintenancethereof. This enables the operation of the furnace to be carried out ina consistent and continuous manner over a very long period of time,thereby achieving a high thermal efficiency within the furnaces and ahigh yield of the objective metal.

The foregoing object, as well as the operations of the method andapparatus according to the present invention, will become more apparentfrom the following detailed description of the invention and theaccompanying drawing.

In the drawing:

FIG. 1 is a longitudinal cross-section showing the basic arrangement andconnection of the furnaces according to the present invention;

FIG. 2 is an enlarged view showing an overflowing part of the melt inthe smelting furnace to be used in the first process step;

FIG. 3 is an enlarged view of a longitudinal crosssection showing anexample wherein the smelting furnace and the separator are integrallyconstructed;

FIG. 4 is a longitudinal cross-section showing another example of theseparator; and

FIG. 5 is a longitudinal cross-section showing an example wherein awhite metal is produced in the blister furnace 3 shown in FIG. 1.

The method according to the present invention may be applied fortreating copper ore as well as other metal ores such as nickel andcobalt which may be refined by the same or similar reaction as withcopper. The present invention, however, will be described with reference to copper as an example.

The process disclosed in the prior U.S. patent appiication Ser. No.88l,226, now U.S. Pat. No. 3,725,044, comprises three process steps. Thefirst process step for smelting copper ore (formation of matte and slag)and simultaneous recovery of copper content in a slag produced in thesecond process step; the second process step wherein the iron content inthe matte produced in the first process step is oxidized and removed(formation of white metal and slag); and the third process step whereinthe sulfur content in white metal produced in the second process step isoxidized and removed. These three process steps are carried out by useof three furnaces corresponding to the abovementioned. respectiveprocess steps, ie. a smelting furnace, at slagging furnace, and ablister furnace. Each of these furnaces is connected with the other toenable continuous transfer of a melt to be realized therebetween, andeach of the furnaces is so arranged that the compositions, temperatures,and residence quantities of matte, slag, white metal, and blister copperresiding in the furnace may be controlled independently of the other twofurnaces. A blister copper can thereby be produced in a continuousmanner as a whole. In this process, wherein each pro cess step forcopper refining is carried out in a corresponding furnace, it ispossible to control the reaction conditions, mainly the slagcomposition, independently ofthe other two steps. Consequently, in eachindividual furnace, the furnace efficiency in each process step can beincreased without disturbing the discreteness in the furnace operation,which disturbance might arise in a furnace having a plurality ofreaction zones by convection and agitation of the melt formed when rawmate rial and air are supplied. The operational efficiency of the entiresystem can thereby be improved in each process step.

in this method, however, for the reaction products to be tapped outofthe furnace in the state of their being separated each other, thematte and the slag should exist separately in at least a part of eachfurnace, and when furnace efficiency is to be increased to a considerable extent, this would appear to be restrictive. Par ticularly, asthe slag produced in the first process step is an ultimate tailing,reduction of the copper content in this slag to the minimum possibledegree constitutes an important factor affecting the economy of thec0pper refining process.

To overcome this difficulty it is the ordinary practice to provide asettling furnace to recover a part of the copper content residing in theslag as a matte, the copper content existing mainly in the form of mattedispersed in the slag. As the matte to be recovered is small inquantity, it is troublesome and undesirable in actual operation torecycle the matte into the refining process in a continuous manner.

According to the present invention, a separation step is providedsubsequent to the first process step, whereby the function of thesmelting furnace for the first process step is limited to the smeltingof the raw material and absorption of the copper content in a slagformed in the third process step into a matte layer, and the reactionproducts are all tapped out simultaneously without being separated fromeach other. After transfer to the subsequent separation step, thesereaction products are separated and tapped out individually, therebyfurther improving the furnace efficiency of the smelting furnace, andensuring the separation of the matte and the slag more satisfactorily.By providing the separation process, the present invention hassuccessfully achieved reduction in the copper loss as well as orderlyarrangement of the flow path of a melt to facilitate the maintenance andcontrol of the entire system.

More particularly, the present invention may be carried out by properlyarranging a furnace for smelting mainly sulfide ore (smelting furnace),a furnace for separating products formed in the smelting furnace intomatte and slag (separator), and another furnace for oxidizing iron andsulfur contained in the matte to produce white metal or blister copper(blister furnace), each of which is so designed that the composition,temperature. surface level, and interfacial level of a melt therewithinmay be controlled and maintained constant independently of the remainingfurnaces, and the furnaces are further connected with each other bymeans of mutual transfer of the melt therebetween, whereby the entirerefining system may be operated in a continuous manner as a whole. Theessentials of the operations in each furnace and between them will beset forth hereinbelow.

First Process Step (Smelting Process) in this process step, a rawmaterial to be smelted which consists principally of a sulfide ore and aflux (hereinafter referred to simply as raw material), is mixed withfuel and air at an appropriate mixing ratio in accordance withpredetermined reaction conditions such as the grade of matte to beproduced, the composition of slag, furnace temperature, and so forth.The raw material is then fed directly and continuously into a melt bath,which is the reaction products formed in the first process step at aprescribed feed rate per unit time (hereinafter referred to as a rawmaterial feeding rate) and is caused to melt without delay, therebyforming matte and slag. On the other hand, a slag formed in theaforementioned blister furnace (blister furnace slag) is transferredback to the smelting furnace in a substantially continuous manner, andthe major portion of the objective metal contained in the blisterfurnace slag is caused to be absorbed into the smelting furnace mate.Simultaneously, the products formed in the smelting furnace aredischarged out of the furnace in a substantially continuous manner, andthen transferred to the separator for the second process step. The termsubstantially continuous manner" designates a transfer system, in which,even if the transfer of the melt is batchwise from the micro-analyticalstandpoint, the transfer quantity thereof at any one time is so small incomparison with the residence quantity of the melt within the smeltingfurnace that variations in the reaction conditions for such batch systembecomes negligible from the metallurgical standpoint. Furthermore,transfer of the melt from the smelting furnace to the separator iscarried out by gravity, utilizing the difference in the surface levelbetween the two furnaces.

Second Process Step (Separating Process) In this process step, all kindsof the reaction products formed in the first process step arecontinuously charged into the separator and caused to stand therewithinfor a certain period of time, thereby separating matte from slag, andtapping each of these melts continuously out of the separating furnace.

Third Process Step (Blistering Process) In this process step, the matteseparated in and tapped out of the separator (second process step) ischarged into the blister furnace in a substantially continuous manner,while air, flux, and coolant are mixed at an appropriate ratio to bedetermined in accordance with the raw material feeding rate in theforegoing first process step. This admixture is charged directly andcontinuously into a melt within the blister furnace consisting ofreaction products formed in the third process step so as to produce andseparate crude metal and slag (blister furnace slag) without delay, andtap each of these melts out of the blister furnace. The crude metal isthen forwarded to a refining process of known type,

and the blister furnace slag is recycled to the smelting furnace in asubstantially continuous manner so as to be subjected to the treatmentas stated in the foregoing. In this case, transfer of either the crudemetal or the blister furnace slag from the blister furnace to thesmelting furnace or refining process is carried out by the gravity ofthe melt, utilizing the difference in the surface level between thefurnaces concerned (automatic transfer), and the other by physical forcebeing applied from outside (forced transfer).

Furthermore, by maintaining a constant residence quantity of each meltof matte, slag, and crude metal in the respective process steps, therate of production of each melt and the rate of transfer between therespective furnaces are so regulated as to be equilibriated to the rateof feeding of the raw material in the first process step as well as tothe rate of feeding of the coolant in the third process step. At thesame time, the composition, temperature, surface level, and interfaciallevel of the melts in each furnace are controlled independently andmaintained constant, thereby producing the intended metal from thecorresponding ore in a continuous and highly economical manner.

More detailed explanation of the operations of the furnaces according tothe present invention will be made hereinbelow with reference to theaccompanying drawings.

In FIG. 1, a smelting furnace l accommodating slag 4 and matte S isprovided with a lance 6, a burner 7, a melt discharging port 8, a meltoverflow weir 10, and a revert slag charging port 22a; a separatingvessel (or a separator) 2 accommodating matte 11 and slag 12 is providedwith a device 13 for keeping the separator at a required temperature, acharging port 14 for the melts formed in the smelting furnace, adischarging port 15 for a separated slag 12, a matte tapping port 16,and a matte siphon 17', and a blister furnace 3, in which layers ofwhite metal 19, blister copper 20, and slag 21 are held, is providedwith a matte charging port 18, a blister furnace slag discharging port22, a blister copper tapping port 23, a blister copper siphon 24, ablister copper overflow weir 25, and a lance 26.

[n the smelting furnace l, a raw material which is principally composedof sulfide ore and a flux such as a silicic ore is mixed with fuel andair in'a ratio suitable for the predetermined reaction conditions, themixture of which is charged directly and continuously, at apredetermined feed rate, into a melt consisting of the matte 5 and theslag 4 which are the reaction products in the smelting furnace. Whileany practical method may be employed for feeding the mixture material,the raw material is most quickly and efficiently smelted when it iscrushed into a powder or granular form and then blown into the meltcarried on a gas current through the lance provided in the furnace. Alarge quantity of the raw material is thus smelted quickly and thegeneration of dust is prevented. In this case, the pressure of the gassupplied is determined automatically by the inner diameter of the lanceas well as the position of the tip end thereof in a volume which issufficiently high to feed the gas current and the raw material directlyinto the melt. As a result of this, the melt is agitated satisfactorily,and the reaction within the furnace proceeds rapidly, thereby improvingfurnace efficiency. The matte grade may be controlled at any desiredlevel by adjusting the air ratio to the raw material. Here the air ratiosignifies the ratio between the net quantity of air for reaction whichis the balance after subtraction of the quantity of air necessary forcombustion of the fuel from the total air quantity injected into thefurnace. More particularly, when the grade of the matte to be producedis raised. an advantageous generation of heat from theoxidation-reaction of the iron and sulfur contents in the raw materialore can be utilized effectively for smelting the raw material, etc.,whereas the copper loss in the slag inevitably increases. In this case,addition of a reducing agent such as pyrite into the separator, in amanner stated later on, will, to a certain extent, prevent the copperloss from increasing.

Any kind of fuel having fluidity, including solid fuel in a powder form,may be used for the present invention, and, furthermore, the consumptionof the fuel to be used for the smelting may be reduced by substitutingthe whole or a part of air with an equivalent amount of oxygen. Fuel isnecessarily fed to the same place in the furnace as that of the rawmaterial. but it is best blown directly into the melt bath in the samemanner as the raw material for the significantly increased heat transferefficiency. As a result, the temperature of the furnace atmosphere andthe exhaust gas therefrom can be lowered to a level almost equal to thatof the melt with the result that capture and treatment of the exhaustgas is facilitated and the life of the furnace walls is remarkablyextended.

Fuel may be burnt by a burner 7. in this case, the fuel consumption maybe reduced by preheating and/r oxygen-enriching the air for thecombustion.

All of the products formed in the smelting furnace are tapped out of thefurnace through the melt discharging port 8. Explaining this withreference to FIG. 2, which shows an enlarged partial view of the meltdischarging port, the melt formed in the smelting furnace is tapped outof the furnace through the melt discharging port 8, wherein a sealingdamper 9 fitted on the outside of the melt discharging port 8 preventsthe furnace gas from escaping or the atmospheric air from infiltratinginto the furnace. The slag layer 4 retained within the furnace can becontrolled and kept at the required constant thickness by fixing thebottom end 9a of the sealing damper 9 at a certain constant differencein the level which is lower than the melt overflow weir. The sealingdamper 9 should be wide enough for closing the melt discharging port 8and be made movable up and down. The durability of the sealing damper 9may be further increased by means of a water cooling jacket providedthereon. It should be noted that in the case where the matte and theslag are tapped out separately through a siphon and a slag dischargingport 22 directly provided on the furnace, as in the case of the blisterfurnace 3 shown in FIG. 1, it may be difficult to reduce the thicknessof the slag layer to one thinner than a certain critical value (about100 mm) for the purpose of effecting the separation of the matte and theslag to a satisfactory degree, and preventing the matte from mixing intothe slag. [t is, however, possible to form a slag layer having a desiredthickness of even thinner than 50 mm by means of the aforementionedsealing damper 9, whereby the rate of reaction between the melt and theair supplied through the lance is significantly improved.

By maintaining the melt overflow weir I0 and the bottom end 9a of thesealing damper 9 at required constant levels so as to cause theresidence quantities of the matte and the slag to be maintained constantwithin the furnace. the feeding quantity of the melt into the separatorcan be equilibriated with the rate of feeding of the raw material intothe smelting furnace, whereby a constant feed rate may be maintained. Asthe result, the melt is continuously charged into the separator 2 by wayof a launder and through the melt charging port 14, where it is retainedfor a certain period of time until it is separated into the matte 11 andthe slag 12. The slag 12 is then tapped out of the separator through theslag discharging port 15, and dumped as indicated by the arrow 11 eitheras it is or after it has been retained within a settling furnace tosettle the matte particles contained therein. On the other hand, thematte 11 is taken out of the separator through the matte tapping port16, and then the matte siphon 17, after which it is allowed to overflowfrom the matte overflow weir I and fed into the blister furnace 3 in acontinuous mannet.

The separator 2 may be kept at a required temperature by means of aburner (not shown) or an electric heating device 13. Also, as shown inFIG. 3, the separator 2 may be integrated with the smelting furnace 1,thereby simplifying the installation. in this case, by maintaining thelevel 10a of the melt discharging port 8 of the smelting furnace lowerthan the level of the slag discharging port 15 of the separator, theliquid surface in both smelting furnace and separator is made common,and the residence quantities of the matte and the slag within thesmelting furnace are maintained constant. As shown in H6. 4, theseparator 2 may be formed in a shape longitudinally extended in the flowdirection of the melt (e.g. oval, rectangular, etc.) with a matte sump27, a matte siphon l7, and a melt charging port 14 being provided at oneend, and a slag discharging port 15 provided at the other end, wherebythe matte particles in the slag can be more perfectly sedimented. Inthis case, the rate of recovery of the copper content in the slag may befurther increased by addition of a reducing agent such as pyrite, coke,and so on. The matte separated in the separator and a matte newlyproduced as the result of extraction of the copper content from the slagby addition of pyrite are tapped out of the furnace 2 together throughthe matte tapping port 16 and then the matte siphon 17, the entire matteas combined being then fed into the blister furnace 3. In either case,thickness of each of the matte layer and the slag layer retained in theseparator can be kept at a fixed value by maintaining constant heightsof the slag discharging port and the matte overflow weir, respectively.As a consequence, the flow rates of the slag and the matte areequilibriated with the feed rate of the melt transferred from thesmelting furnace.

The matte from the separator 2 is continuously charged into a melt bathin the blister furnace 3 consisting of blister furnace slag 21, whitemetal 19, and blister copper 20, all of which are reaction products inthe third process step, while air and a flux are simulta neously fed indirectly and continuously. A coolant (or cold dope) containing theobjective metal such as the raw material or scrap to be charged into themelt bath can be fused by the excessive heat generated in this thirdprocess step, thereby preventing the furnace temperature from exceedingthe ordinary operating temperature, and simultaneously allowing theentire treating capacity of the ore to further increase. These materialsare fed into the blister furnace through lance 26 provided in the samemanner as in the smelting furnace. The total quantity of the air to beintroduced into the blister furnace should be sufficient to convert thetotal quantities of the matte and the coolant to be charged into theblister furnace slag and a blister copper. and the thickness of a whitemetal layer residing in the furnace is maintained constant. The blistercopper is tapped out of the furnace through the blister copper tappingport 23 and then the blister copper siphon 24. after which it is causedto continuously overflow from the blister copper overflow weir 25, andis forwarded to the refining process of known type. On the other hand,the blister furnace slag is continuously dis charged out of the furnacethrough the blister furnace slag discharging port 22, the melt transferpassage g, and recycled to the revert slag charging port 22a provided inthe smelting furnace in a substantially continu ous manner by a forcedtransfer. Any practical means such as a bubble pump (airlift), a bucketconveyor operated in a continuous motion, an electromagnetic transfer,and so on may be employed for the forced transfer.

Transfer of the blister furnace slag to the smelting furnace ispreferably achieved in the molten state, taking advantage of its owntemperature. However, it is also possible to transfer the blisterfurnace slag in the solidified or granulated form to facilitatehandling. In case the grade of matte is high and the formation ofblister furnace slag is small, increase in the fuel consumption requiredfor remelting the blister furnace slag is not so large in comparisonwith what will be required in the event that the matte grade is low andthe quantity of the blister furnace slag is large.

In the above-described example, the level of the melt bath in theseparator is kept lower than that in the smelting furnace, and the meltbath level in the blister furnace is kept far lower than that in theseparator, whereby the transfer of the matte is carried out by thegravity of the melt, taking advantage of the difference in head amongthese three furnaces. On the other hand, when the surface level of themelt in the blister furnace is higher than that in the smelting furnace,the transfer of the blister furnace slag is carried out by the gravitythereof, whereas the transfer of the matte f om the separator to theblister furnace may be accomplished by a forced transfer.

While metal 19 is an intermediate product of the blister making step.which is not tapped out but is maintained in a constant residencequantity by adjusting the reaction conditions.

The thickness and residence quantity of each of the melt layers in theblister furnace can be maintained constant by setting the slagdischarging port and the blister copper overflow weir 25 at constantlevels in the same manner as in the separator. As a result, the rates ofproduction of the slag and the blister copper in the blister furnace arecontrolled by the rate of feeding of the matte (which is governed by thereaction conditions and the rate of feeding of the raw material in thesmelting furnace) and the rate of feeding of the coolant into theblister furnace (which is governed by the grade of the matte to be fedinto the blister furnace and the reaction conditions therewithin). Inthis way, the entire reaction system can be controlled under certainconstant reaction conditions.

The reaction in the blister furnace may also be carried out under theco-existence of the two phases of slag and blister copper only, withoutthe presence of a white metal in the furnace, by charging a greaterquantity of air into the furnace than required to oxidize principallythe entire quantities of iron and sulfur contained in the matte and thecoolant. In this case. the sulfur content in the blister copper can bereduced below the saturated concentration thereof by increasing theratio of air to be supplied to a desired extent. That is, as the ratioof air increases, the copper content in the slag is also increased,whereas the sulfur content in the blister copper is decreased. Here, theair ratio signifies the ratio of air to the total quantities of thematte and cool ant. When a white metal layer exists in the blisterfurnace, the copper content in the slag ranges from 2 to 6 percent,whereas the copper content may be increased to a range of from 40 to 50percent when no white metal is present in the furnace. However, thematte grade and the reaction conditions in the blister furnace should beset within such a range where the copper content in the slag formed inthe blister furnace does not exceed the copper content in the materialsfed thereinto, and, further, the flux (particularly lime) fed into theblister furnace does not exceed the amount which is needed in the entiresystem. In the ordinary converter process, silica sand is used as aflux, whereas, in the blister furnace according to the presentinvention. the fluidity of the slag formed can be increased by use oflime or a mixture of lime and silica sand.

Exhaust gas discharged from each furnace in the above-stated processsteps in collected and let out through a flue duct 0, and the totalquantity thereof is cooled and utilized as a raw material for productionof sulfuric acid.

According to another embodiment of the present invention, the thirdprocess step may be further divided into two stages to conduct theentire furnace operations in four process steps. In this case, the thirdpro cess step carries out production of white metal and blister furnaceslag in the blister furnace 3. More particularly, as shown in FIG. 5,while the matte is being continuously fed into the blister furnacethrough the matte charging port 18, air and a flux are charged throughthe lance 26 into the melt which is composed of the blister furnace slag2] and the white metal 19 formed by the reaction within the furnace. Theexcess heat generated at this time is utilized for melting the 'coolantin the same manner as in the previous example. Air should be charged atthe required feed rate to oxidize principally the entire part ofiron anda part of sulfur contained in the matte and the coolant fed into thefurnace, respectively, and to produce a white metal and a slag. The fluxused in this case may be silica sand as in the ordinary slag-formingprocess using a converter.

The slag 21 is then caused to flow continuously out of the furnacethrough the slag discharging port 22, and, as in the previous example.is transferred and recycled into the smelting furnace. It has beenconfirmed that the copper content in the slag exists principally in theform of white metal particles and metallic copper particles. instead ofreturning the slag into the smelting furnace in a molten state, it maybe crushed and treated by floatation, concentrating the copper content,after which the concentrate may be recycled to the smelting furnace.

On the other hand, the white metal 19 is tapped out of the furnacethrough the tapping port 23 and then the siphon 24, thereafter flowingover the overflow weir 25. The white metal, which is principallycomposed of a single or a plurality of the objective metal sulfides mayin some cases be regarded as the final product in this treating process.For instance, when the objective metal is nickel, the white metal isforwarded as it is to an electrolytic process, or transferred to areducing process after it has been crushed and roasted. Further more,when the white metal produced from a raw material contains two or morekinds of metals such as copper, nickel, and cobalt in such quantitiesthat none of these metals can be neglected from the economical ortechnical standpoint. The white metal is then processed to separate theobjective metals from each other by such means as, for example, afloatation treatment after it has been slowly cooled. When a white metalis principally composed of sulfides of copper, the white metal istransferred in its molten state to another blister furnace, wherein thefourth process step is carried out. The blister furnace used in thisfourth process step may be an ordinary converter, but is preferablyanother unit of blister furnace according to the present invention,whereby the white metal can be treated in a continuous manner. Theoperational process of the fourth process step is exactly the same asthat of the third process step in the foregoing first embodiment, exceptthat the ma terial processed is the white metal and the quantity of slagproduced is extremely small. The quantity of the slag produced from thewhite metal is less than l percent by weight of the white metal,normally in a range of from 2 to 6 percent, with the result thattransfer of the slag in its molten state back to the smelting furnacebecomes somewhat difficult. In this situation, the slag tapped out ofthe furnace is solidifed and then charged together with the other rawmaterials into the smelting furnace.

In order to restrain the slag formation in the fourth process step, acoolant which is not contributive to the slag formation, such as a scrapof the objective metal, may be fed into the blister furnace for thefourth process step.

The treatment of exhaust gas discharged from this blister furnace can bedone in the same manner as in the aforementioned first embodiment.

The above-described process according to the present invention has notonly the generally known advantages associated with a continuous processsuch as a lower cost for construction and operations than the batchsystem, and facilitating the introduction of an automatic controlsystem, but also the following additional features owing to the uniqueprocess steps and reaction system thereof.

In the process according to the present invention, the smelting furnacefunctions only for reaction (i.e., smelting) of the raw material, whilethe separation of slag and matte produced in this smelting furnace iscarried out in the separator. The agitation of the melt in the smeltingfurnace can be performed without any restriction and the charges such asthe raw material can be fed into the furnace covering the largestpossible area of the furnace bed with the result that the furnaceefficiency (i.e., smelting rate) is remarkably improved. Furthermore,the thickness of the slag layer formed in the smelting furnace can bedecreased and, at the same time, the agitation of the melt can bestrengthened, so that the contact between the matte and the slag becomes satisfactory, and the copper content in the revert slag (blisterfurnace slag) is absorbed quickly and completely into the matte phaseuntil equilibrium is reached.

It has been confirmed by a microscopic observation on a quenched samplethat, under the reaction conditions according to the present invention,most of the copper content in the slag exists in the form of mattegranules, each having a diameter of from about 0.5 to about 3 mm. Thecopper granules were found to have settled rapidly as readily calculatedfrom the Stokes equation and could be separated from the slag easily inthe separation furnace. so that a satisfactory result could be obtainedwithout installing a settling furnace along with the separator.

The thickness ofthe slag layer in the smelting furnace according to thepresent invention could be reduced to as thin as l/lO to 1/20 of thatformed in an ordinary rcverberatory furnace. As the result of this, asufficiently high rate of reaction in the furnace can be achieved, evenif the pressure of air to be blown into the melt was low, withoutimmersing the tip end ofthe lance into the melt. This makes for aconsiderable saving in pot'er consumption and results in the extendedlife of the lance. in other words, as the air reacts mainly with thematte, and as there is only an extremely thin layer of the slag in themelt bath, the contact between the air and the matte is improved, sincethe slag layer does not prevent the air from contacting the matte. Thereaction rate in the furnace is thereby significantly increased.

Also. a reducing agent such as pyrite may be added in the separator tofurther improve the rate of recovery of copper. In this case, therecovered matte is merged into the smelting furnace matte, separatedwithin the separator, and continuously transferred in its entirety intothe blister furnace through the one and same flow path, so that the meltflow path can be simplified and furnace control is facilitated. (It is awell-known fact that, when a flowing quantity of the melt in the launderis small, great difficulty is experienced in the transfer operation.)

Furthermore, in the process according to the present invention,corrosion of the bricks constituting the fur nace is suppressed. Slag isthe principal cause of corrosion of the bricks and in the presentprocess, the slag layer is extremely thin, hence the area of contactbetween the slag and the furnace walls is small. This eliminates theadded expense resulting from the use of a refractory material or jackethaving exceptional durability (these being most expensive, of course) tocover such contact area.

In order to reduce the present invention practice, the followingpreferred examples are presented. it should, however, be noted thatthese examples are just illustrative, and do not intend to limit thescope of the present invention as set forth in the appended claims.

EXAMPLE 1 6,000 kg per hour of a copper concentrate consisting of 24.0percent of copper, 34.2 percent of iron, 34.2 percent of sulfur, and 3.7percent of SiO 1,500 kg per hour of silica sand containing 90.0 percentof SiO:, and 500 kg per hour of lime stone containing 53.4 percent ofCaO were directly charged into a melt bath which was the reactionproduct in the smelting furnace together with L500 Nm per hour of airhaving a gauge pressure of 2 kg per square centimeter through a lanceprovided in the furnace. By use of another lance, 2,500 Nrn per hour ofair having a gauge pressure of 0.8 kg

per square centimeter and 500 Nm per hour of oxygen for industrial usewere mixed. The mixed gas was directly charged into the melt bath in thesame manner as was done with the above raw material. The raw materialhad all been previously classified into granules, each having a diameterof less than l mm, and dried until the water content thereof ranged fromI to 2 percent.

On the other hand, 250 liters per hour of fuel oil was burnt with theaid of 2,500 Nm" per hour of air having a gauge pressure of 0.2 kg persquare centimeter and preheated to 300C by use of a burner provided ontop of the furnace. A blister furnace slag was fed into the furnacethrough a blister furnace slag charging port provided therein. Thicknessof the slag layer within the furnace was maintained at about 20 mm. Theproducts consisting principally of matte and slag were caused tocontinuously flow out of the furnace through a melt discharging portprovided in the furnace and further caused to flow into a separator bythe gravity thereof. The 50;. content in the exhaust gas discharged fromthe smelting furnace was from 8 to l0 percent. The tempcrature withinthe furnace was kept in a range of from 1,220" to l,260C by adjustingthe fuel supply there into.

The separator employed herein was of the type shown in H0. 4, and itscapacity to hold the melt was about l0 tons. l50 kg per hour of pyritecontaining 45 percent of sulfur and 50 kg per hour of coke breeze werecharged into the separator. The thickness of the slag layer and theresidence quantities of slag and matte within the separator were keptconstant by maintaining a matte overflow weir at a level 120 mm lowerthan a slag overflow weir also provided in the separator. The slag wascaused to flow out of the separator through a slag discharging portprovided in the separator and then granulated with water jet. The slagquantity thus produced was 5,600 kg per hour and the composition thereofwas controlled to be from 0.4 to 0.6 percent of copper, from 33 to 35percent of SiO and from 5 to 6 percent of CaO. The matte wascontinuously tapped out of the furnace through a siphon provided thereinand fed into a blister furnace. The grade of the matte thus produced wascontrolled to contain from 59 to 62 percent copper.

200 kg per hour of the above-mentioned silica sand, [00 kg per hour oflime stone, and 100 kg per hour of precipitate containing 60 percentcopper, together with 2,400 Nm per hour of air at a gauge pressure of 2kg per square centimeter were charged into the blister furnace. Thecharges were supplied directly into the melt bath formed by reactionthrough a lance provided in the furnace. The copper content in the slagformed in the furnace was controlled to be from to percent with theresult that no white metal was formed in the furnace and the melt bathformed was found to have been composed of two layers of slag and blistercopper respectively. The slag thus formed was composed of from 8 to 13percent of SiOr from 4 to 6 percent of (210, and from 38 to 45 percentof iron (most of the iron b ing composed of Fe O The slag was thencaused to continuously flow out of the furnace through a slagdischarging port provided in the furnace, and transferred to theaforementioned smelting furnace by a bucket conveyor being operated incontinuous mo tion. The blister copper, on the other hand, was caused toflow out of the furnace through a siphon provided LII contiguous to theblister copper tapping port. The rate of production of the blistercopper was 1,550 kg per hour, and its composition was from 98 to 99percent of copper and from 0.2 to 0.3 of sulfur.

When adjustment was made so as to cause a white metal layer to form inthe blister furnace by changing the rate of feeding of theaforementioned silica sand and lime stone into the smelting furnace to1,700 and 350 kg per hour, respectively, and by changing the kind of theflux to be fed into the blister furnace to lime stone at a rateoffeeding of 250 kg, and by reducing the rate of feeding of air into theblister furnace by approximately 2 percent less than the aforedescribedexample, the slag produced was found to be composed of from 6 to 8percent of copper, from 12 to l6 percent of Ca(), and from 55 to percentF630,, and the quantity of copper recycled to the smelting furnace wasreduced, whereas the surfur content in the blister copper increased to 1percent and above. Furthermore, it was observed that the fluidity of theslag tended to lower, when the content of calcium oxide (CaO) in theslag was reduced to 5 to 7 percent.

The rate of production of the blister furnace slag was approximatelyl,000 to 1,500 kg per hour. In such case of low rate of production ofthe slag, a portion of the slag solidifed in the course of its transferto the smelting furnace, but this in no way adversely affected theoperation of the smelting furnace. Sulfur dioxide (S0 contained in theexhaust gas discharged from the blister furnace was from l4 to 16percent, and the temperature within the furnace was from l,200 tol,270C.

The exhaust gas from each furnace was collected and cooled, after whichit was delivered to a sulfuric acid production plant. The flue dustcontained in the exhaust gas collected in the dust chamber was foundfrom I to 2 percent with respect to the total quantity of the rawmaterial used.

EXAMPLE 2 5,000 kg per hour of copper concentrate consisting of 18.9percent of copper, 33.8 percent of iron, 36.5 percent of sulfur, and L5percent of silicic acid, 1,400 kg per hour of silica sand containingtherein 89 percent of SiOt 570 kg per hour of lime stone containingtherein 53.4 percent of CaO together with 200 Nm per hour of air at agauge pressure of 2 kg per square centimeter were charged into thesmelting furnace. The charges were supplied directly into the melt bathcomposed of reaction products within the furnace through a lanceprovided therein together with 3,000 Nm per hour of air at a gaugepressure of 0.8 kg per square centimeter and 5 l0 Nm per hour of oxygengas for industrial use. At the same time, l60 liters per hour of fueloil was blown into the furnace together with 1,700 Nm per hour of air ata gauge pressure of 0.8 kg per square centimeter through a separatelance, and was burnt therewithin. In the meantime, blister furnace slagwas continuously charged into the smelting furnace through the blisterfurnace slag charging port provided. The matte and slag thus producedwere introduced into a separator which had been integrally formed withthe smelting furnace as shown in FIG. 3, thereby to separate matte andslag from each other. The slag layer within the smelting furnace wasmaintained in a thickness of 20 mm. Also, the rate of feeding of fuelwas so adjusted as to maintain the temperature within the furnace in arange offrom 1,220 to l,270C. The exhaust gas discharge from thesmelting furnace was found to have contained from 13 to lo percent S Inthe separator, the matte overflow weir provided was set at a certainlevel. which was lower by 70 mm than the level of the slag outlet portalso provided therein, whereby the slag layer within the furnace wasmaintained in a thickness of about 300 mm. The slag thus formed wascaused to continuously flow out of the furnace through the slagdischarging port. and then water-granulated. The composition of the slagwas controlled to have from 32 to 34 percent of SK); and from S to 6percent of CaO. The slag contained from 0.30 to 0.45 percent of copperand the rate of production thereof was 5,900 kg per hour. The matte thusproduced, on the other hand, was caused to flow continuously out of thefurnace through a siphon provided continguous to the matte tapping port,and then charged into the blister furnace. The matte was controlled tocontain from 39 to 42 percent copper.

1,000 kg per hour of the aforementioned raw marerial ore and 500 kg perhour of silica sand together with 3,040 Nm per hour of air at a gaugepressure of 2 kg per square centimeter were charged into the blisterfurnace. The charges were fed directly into a melt bath consisting ofthe reaction products formed by reaction within the furnace. Thereaction products were composed of white metal and slag, and the slaglayer within the furnace was kept at about l00 mm thick. The slag thusproduced was caused to continuously flow out of the furnace through aslag discharging port provided therein, and then recycled to thesmelting furnace by means of a bubble pump. The slag contained from 22to 24 percent SiO and from 2 to 6 percent copper, and the rate ofproduction thereof was about 2,300 kg per hour according to calculation.The white metal thus produced, on the other hand, was caused tocontinuously flow out of the furnace through a siphon providedcontiguous to the white metal tapping port and then forwarded to acopper refining process of known type. The white metal was controlled tocontain from 77 to 79 percent of copper. The sulfur content therein wasfrom I) to percent, and the temperature within the furnace was froml,25() to l,300C. The exhaust gas discharged from the furnace containedfrom 13.5 to 15.0 percent of 80 The exhaust gas from each furnace wastreated in the same manner as stated in Example I.

It is of course possible that various modification in the refiningprocess may be made by employing the existing copper refining facilitieswithout changing the basic principles of the present invention. Forexample, in the first process step, a heretoforeknown reverbera' toryfurnace or an electric furnace may be employed in place of theabovementioned smelting furnace according to the present invention. Inthis case. a revert slag charging port is provided therein, as the casemay be, through which the blister furnace slag is charged into thefurnace. Further, in order to control the grade of the matte produced, alance may be provided in these substitute furnaces in the same manner asin the foregoing smelting furnace according to the present invention tosupply air into a melt bath within the furnace, or the whole or a partof the ore may be roasted beforehand.

In the first process step, a heretofore-known flushsmelting furnace orblast furnace may be employed singly or in combination with the smeltingfurnace according to the present invention. In the latter case, theproducts formed in these two furnaces are all charged into a separatorprovided subsequent to the first furnace, whereas the blister furnaceslag is charged into the smelting furnace only according to the presentinvention, whereby treatment of the slag can be done efficiently.

What we claim is:

l. A method for the continuous production of blister copper from sulfidecopper ores in a smelting furnace unit, a separator furnace unit and anoxidizing furnace unit, each controllable in operation independently ofthe other as to compositions of melts therein, temperatures, levels offree surfaces of corresponding melts, and the thickness of the layers ofthe individual melts in the separator furnace unit and the oxidizingfurnace unit including the corresponding slag therein, and wherein therates of production of slag, matte and blister copper, the rate oftransfer of matte from the sepa rator furnace unit to the oxidizingfurnace unit and the rates oftransfer of blister copper and slag out ofthe oxidizing furnace unit are maintained in constant equilibrium withthe rate of transferring smelted inputs from the smelting furnace unitto the separator furnace unit. which method comprises the steps of:

a. continuously smelting in the smelting furnace unit inputs of sulfidecopper ores, flux and oxygencontaining gas to yield a lower layer ofmatte and an upper layer of slag;

b. simultaneously, while smelting said inputs, continuously transferringsaid matte and slag in admix ture from said smelting furnace unit to aseparator furnace unit, at a rate of transfer balancing the rate ofproduction of matte and slag. wherein the matte and the slag arepermitted to separate;

c. continuously transferring slag out of said separator furnace unit fordisposal at a rate balancing the rate of transfer of slag from thesmelting furnace and continuously transferring matte out of said separator furnace unit to an oxidizing furnace unit at a rate of transferbalancing the rate of transfer of matte from the smelting furnace, bothrates of transferring matte and slag being equal to the rate oftransferring said matte and slag in admixture from the smelting furnaceunit to the separator furnace unit by retaining a constant thickness ofslag layer and a constant thickness of matte layer in the separatorfurnace unit, such that a definite amount of the matte is continuouslytransferred to said oxidizing furnace unit, which amount is equal to theamount transferred to the separator;

d. introducing into said oxidizing furnace unit, flux and anoxygen-containing gas to convert said matte to blister copper and slagto produce layers thereof in said oxidizing furnace; and

e. simultaneously, while oxidizing said matte in said oxidizing furnaceunit, continuously transferring said blister copper out of saidoxidizing furnace unit at a rate of transfer balancing the rate ofproduction of said blister copper and simultaneously transferring saidslag out of said oxidizing furnace unit at a rate balancing the rate ofproduction of the slag in said oxidizing furnace unit, both rates oftransferring the blister copper and the slag produced in said oxidizingfurnace unit being balanced to the rate of feeding said matte, flux andoxygencontaining gas to said oxidizing furnace unit by retaining in saidoxidizing furnace unit a constant thickness of the slag layer and aconstant thickness of the blister copper layer, and the rates oftransferring said blister copper and said slag out of said oxidizingfurnace unit thereby being balanced to the rate of transferring saidmatte and slag in admix ture out of the smelting furnace unit to theseparator furnace unit.

2. The method according to claim I, wherein said slag produced in saidoxidizing furnace unit is introduced into said smelting furnace unit.

3. The method for continuous extraction and produc tion of a white metalwhich is a sulfide of a metal selected from the group consisting ofnickel, cobalt, copper, and mixtures thereof from the correspondingsulfide metal ore in a smelting furnace unit, a separator furnace unitand an oxidizing furnace unit, each controllable in operationindependently of the other as to compositions of melts therein,temperatures, levels of free surfaces of corresponding melts, and thethickness ofthe layers of the individual melts in the separator furnaceunit and the oxidizing furnace unit including the corresponding slagtherein, wherein the rates of production of slag and matte and whitemetal, the rate of transfer of the matte from the separator furnace unitto the oxidizing furnace unit to be converted into white metal, and therates of transfer of the white metal and slag out of the oxidizingfurnace unit are maintained in constant equilibrium with the rate oftransferring smelted inputs from the smelting furnace unit to theseparator furnace unit, which method comprises the steps of:

a. continuously smelting in the smelting furnace unit inputs of sulfideores, flux and oxygen-containing gas to yield a lower layer of a matteand an upper layer of slag;

b. simultaneously, while smelting said inputs, continuously transferringsaid matte and slag in admixture from said smelting furnace unit to aseparator furnace unit, at a rate of transfer balancing the rate ofproduction of said matte and slag, whereby the matte and the slag arepermitted to separate into layers,

c. continuously transferring said slag out of said separator furnaceunit for disposal at a rate of transfer balancing the rate of transferof the slag from the smelting furnace unit and continuously transferringthe matte out of the separator furnace unit to an oxidizing furnace unitat a rate of transfer balancing the rate of transfer of matte from thesmelting furnace, both rates of transferring the slag and the mattebeing equal to the rate of transferring said slag and matte from thesmelting furnace unit to the separator furnace unit by retaining aconstant thickness of slag layer and a constant thickness of matte layerin the separator unit furnace, such that a definite amount of matte istransferred to the oxi dizing unit furnace, which amount is equal to theamount transferred to the separator;

d. introducing into said oxidizing furnace unit flux andoxygen-containing gas to oxidize the matte into white metal and slag toproduce layers thereof in said oxidizing furnace unit; and

e. simultaneously, while oxidizing said matte into white metal in saidoxidizing furnace unit, continuously transferring the white metal out ofsaid oxi dizing furnace unit at a rate balancing the production of thewhite metal and simultaneously transferring said slag out of saidoxidizing furnace unit at a rate balancing the rate of production of theslag in said oxidizing furnace unit, both rates of transferring saidwhite metal and slag produced in said oxidizing furnace unit beingbalanced to the rate of feeding of said matte, flux andoxygen-containing gas to said oxidizing furnace unit by retaining insaid oxidizing furnace unit a constant thickness of the slag layer and aconstant thickness of the white metal, and the rates of transferringsaid white metal and slag out of said oxidizing furnace unit therebybeing balanced to the rate of transferring said matte and slaginadmixture out of the smelting furnace unit to the separator furnaceunit.

4. The method according to claim 3, wherein said slag produced in saidoxidizing furnace unit is introduced into said smelting furnace unit.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION pa e 3 ,890 ,139Dated June 17 ,1975

Inventor(g) SUZUKI et 6.1.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

First page, Col. 1, in the line designated "[73] relating to theassignee's name, change "Kizoku" to Kinzoku Signal and Scaled thisthirtieth Day of December 1975 [SEAL] Arrest:

RUT" C. MASON C. Amul- DAN" Alluring Officer Commissioner of Hue-u andTrademarks

1. A METHOD FOR THE CONTINOUS PRODUCTION OF BLISTER COPPER FROM SULFIDECOPPER ORES IN A SMELTING FURNACE, UNIT, A SEPARATOR FURNACE UNIT AND ANOXIDIZING FURNACE UNIT, EACH CONTROLLABLE IN OPERATION INDEPENDENTLY OFTHE OTHER AS TO COMPOSITIONS OF MELTS THEREIN, TEMPERATURES, LEVELS OFFREE SURFACES OF CORRESPONDING MELTS, AND THE THICKNESS OF THE LAYERS OFTHE INDIVIDUAL MELTS IN THE SEPARATOR FURANCE UNIT AND THE OXIDIZINGFURNACE UNIT INCLUDING THE CORRESPONDING SLAG THEREIN, AND WHEREIN THERATES OF PRODUCTION OF SLAG, MATTE AND BLISTER COPPER, THE ATE OFTRANSFER OF MATTE FROM THE SEPARATOR FURNACE UNIT TO THE OXIDIZINGFURNACE UNIT AND THE RATES OF TRANSFER OF BLISTER COPPER AND SLAG OUT OFTHE OXIDIZING FURNACE UNIT ARE MAINTAINED IN CONSTANT EQUILIBRIUM WITHTHE RATE OF TRANSFERRING SMELTED INPUTS FROM THE SMELTING FURANCE UNITTO THE SEPARATOR FIRNACE, UNIT, WHICH METHOD COMPRISES THE STEPS OF: A.CONTINOUSLY SMELTING IN THE SMELTING FURNACE UNIT INPUTS OF SULFIDECOPPER ORES, FLUX AND OXYGEN-CONTAINING GAS TO YEILD A LOWER ALYER OFMATTE AND AN UPPER LAYER OF SLAG; B. SIMULTANEOUSLY, WHILE SMELTING SAIDINPUTS, CONTINOUSLY TRANSFERRING SAID MATTE AND SLAG IN ADMIXTURE FROMSAID SMELTING FURNACE UNIT TO A SEPARATOR FURNACE, UNIT, AT A RATE OFTRANSFER BALANCING THE RATE OF PRODUCTION OF MATTE AND SLAG, WHEREIN THEMATTE AND THE SLAG ARE PERMITTED TO SEPARATE, C. CONTINOUSLYTRANSFERRING SLAG OUT OF SAID SEPARATOR FURNACE UNIT FOR DISPOSAL AT ARATE BALANCING THE RATE OF TRANSFER OF SLAG FROM THE SMELTING FURNACEAND CONTINUOUSLY TRANSFERRING MATTE OUT OF SAID SEPARTOR FURNACE UNIT TOAN OXIDIZING FURNACE UNIT AT A RATE OF TRANSFER BALANCING THE RATE OFTRANSFER OF MATTE FROM THE SMELTING FURNACE, BOTH RATES OF TRANSFERRINGSAID MATTE AND SLAG BEING EQUAL TO THE RATE OF TRANSFERRING SAID MATTEAND SLAG IN ADMIXTURE FROM THE SMELTING FURNACE UNIT TO THE SEPARATORFURNACE UNIT BY RETAINING A CONSTANT THICKNESS OF SLAG LAYER AND ACONSTANT THICKNESS OF MATTE LAYER IN THE SEPARATOR FURNACE UNIT, SUCHTHAT A DEFINITE AMOUNT OF THE MATTE IS CONTINUOUSLY TRANSFERRED TO SAIDOXIDIZING FURNACE UNIT, WHICH AMOUNT IS EQUAL TO THE AMOUNT TRANSFERREDTO THE SEPARATOR; D. INTRODUCING INTO SAID OXIDIZING FURNACE UNIT, FLUXAND AN OXYGEN-CONTAINING GAS TO CONVERT SAID MATTE TO BLISTER COPPER ANDSLAG TO PRODUCE LAYERS THEREOF IN SAID OXIDIZING FURNACE; AND E.SIMULTANEOUSLY, WHILE OXIDIZING SAID MATTE IN SAID OXIDIXING FURNACEUNIT, CONTINOUSLY TRANSFERRING SAID BLISTER COPPER OUT OF SAID OXIDIZINGFURNACE UNIT AT A RATE OF TRANSFER BALANCING THE RATE OF PRODUCTION OFSAID BLISTER COPPER AND SIMULTANEOUSLY TRANSFERRING SAID SLAG OUT OFSAID OXIDIZING FURNACE UNIT BY RETAINING IN SAID OXIDIZPRODUCTION OF THESLAG IN SAID OXIDIZING FURNACE UNIT, BOTH RATES OF TRANSFERRING THEBLISTER COPPER AND SLAG PRODUCED IN AID OXIDIZING FURNACE UNIT BEINGBALANCED TO THE RATE OF FEEDING SAID MATTE, FLUX AND OXYGEN-CONTAININGGAS TO SAID OXIDIZING FURNACE UNIT BY RETAINING IN SAID OXIDIZINGFURNACE UNIT A CONSTANT THICKNESS OF THE SLAG LAYER AND A CONSTANTTHICKNESS OF THE BLISTER COPPER LAYER, AND THE RATES OF TRANSFERRINGSAID BLISTER COPPER AND SAID SLAG OUT OF SAID OXIDIZING FURNACE UNITTHEREBY BEING BALANCED TO THE ATE OF TRANSFERRING SAID MATTE AND SLAG INADMIXTURE OUT OF THE SMELTING FURNACE UNIT TO THE SEPARTOR FURNACE UNIT.2. The method according to claim 1, wherein said slag produced in saidoxidizing furnace unit is introduced into said smelting furnace unit. 3.The method for continuous extraction and production of a white metalwhich is a sulfide of a metal selected from the group consisting ofnickel, cobalt, copper, and mixtures thereof from the correspondingsulfide metal ore in a smelting furnace unit, a separator fUrnace unitand an oxidizing furnace unit, each controllable in operationindependently of the other as to compositions of melts therein,temperatures, levels of free surfaces of corresponding melts, and thethickness of the layers of the individual melts in the separator furnaceunit and the oxidizing furnace unit including the corresponding slagtherein, wherein the rates of production of slag and matte and whitemetal, the rate of transfer of the matte from the separator furnace unitto the oxidizing furnace unit to be converted into white metal, and therates of transfer of the white metal and slag out of the oxidizingfurnace unit are maintained in constant equilibrium with the rate oftransferring smelted inputs from the smelting furnace unit to theseparator furnace unit, which method comprises the steps of: a.continuously smelting in the smelting furnace unit inputs of sulfideores, flux and oxygen-containing gas to yield a lower layer of a matteand an upper layer of slag; b. simultaneously, while smelting saidinputs, continuously transferring said matte and slag in admixture fromsaid smelting furnace unit to a separator furnace unit, at a rate oftransfer balancing the rate of production of said matte and slag,whereby the matte and the slag are permitted to separate into layers; c.continuously transferring said slag out of said separator furnace unitfor disposal at a rate of transfer balancing the rate of transfer of theslag from the smelting furnace unit and continuously transferring thematte out of the separator furnace unit to an oxidizing furnace unit ata rate of transfer balancing the rate of transfer of matte from thesmelting furnace, both rates of transferring the slag and the mattebeing equal to the rate of transferring said slag and matte from thesmelting furnace unit to the separator furnace unit by retaining aconstant thickness of slag layer and a constant thickness of matte layerin the separator unit furnace, such that a definite amount of matte istransferred to the oxidizing unit furnace, which amount is equal to theamount transferred to the separator; d. introducing into said oxidizingfurnace unit flux and oxygen-containing gas to oxidize the matte intowhite metal and slag to produce layers thereof in said oxidizing furnaceunit; and e. simultaneously, while oxidizing said matte into white metalin said oxidizing furnace unit, continuously transferring the whitemetal out of said oxidizing furnace unit at a rate balancing theproduction of the white metal and simultaneously transferring said slagout of said oxidizing furnace unit at a rate balancing the rate ofproduction of the slag in said oxidizing furnace unit, both rates oftransferring said white metal and slag produced in said oxidizingfurnace unit being balanced to the rate of feeding of said matte, fluxand oxygen-containing gas to said oxidizing furnace unit by retaining insaid oxidizing furnace unit a constant thickness of the slag layer and aconstant thickness of the white metal, and the rates of transferringsaid white metal and slag out of said oxidizing furnace unit therebybeing balanced to the rate of transferring said matte and slag inadmixture out of the smelting furnace unit to the separator furnaceunit.
 4. The method according to claim 3, wherein said slag produced insaid oxidizing furnace unit is introduced into said smelting furnaceunit.